In the field of photography, polymeric compounds are used in a photographic element constituting a photographic light-sensitive material, such as a support layer, an undercoat layer, an intermediate layer, an emulsion layer, a protective layer, a backing layer, an image receiving layer, a barrier layer, a timing layer, an antihalation layer, an antistatic layer, a peeling layer, a mordant layer and a scavenger layer, as described, e.g., in Shell Polymer, Vol. 5, p. 15 (1981). These compounds include various species, for example, natural polymers and their derivatives such as gelatin and acetylcellulose, polycondensation polymers such as polyethylene terephthalate, polymers derived by ring opening polymerization such as polyethylene oxide, and polymers derived by vinyl polymerization such as polyvinyl pyrrolidone and polyvinyl alcohol. As many ethylenically unsaturated monomers have recently been developed with advances in the synthetic polymer industry, polymeric compounds obtained by vinyl polymerization have come into widespread use. Although many homopolymers of ethylenically unsaturated monomers are used as such polymeric compounds obtained by vinyl polymerization, the recent trend has been to use in greater quantities copolymers of dissimilar ethylenically unsaturated monomers as photographically useful polymeric compounds having many functions in order to meet the requirements for improved photographic properties such as "instantaneous photographing" and "increased sensitivity". Many patent applications have been filed and published which are directed to the use of polymeric compounds obtained by copolymerization as part of photographic elements.
Generally, many such copolymers are "random copolymers", in which the constituent units of dissimilar ethylenically unsaturated monomers are arranged at random. Since the mixing of dissimilar ethylenically unsaturated monomers in the preparation of the "random copolymer" is monomer-with-monomer mixing, it is easy to obtain a homogeneous polymeric compound. However, in many cases, properties which supplement or complete the properties of homopolymers of the individual components cannot be fully exhibited in such copolymers because of the interaction of the individual components. Hence, such random copolymers cannot fully meet the high and various requirements for the functions of polymeric compounds.
In order to meet the high requirements for the functions of polymeric compounds, not only have "random copolymers" been utilized, but also the utilization of composites of polymeric materials having more complicated structures have been extensively studied in recent years. One specific example is the use of "graft copolymers" (or more simply "graft polymers") composed of a single or multiple polymeric chains and a graft of another polymer attached thereto. Generally, two dissimilar polymers are not miscible and so-called "phase separation" occurs. This constitutes a great drawback in polymer blending. The "graft polymers", however, have the outstanding characteristic that since the two different polymers are chemically bound to each other, their phase separation does not form two completely independent phases, but rather microphase separation occurs to form a multiphase structure.
A detailed description of graft polymers is given, for example, in Fumio Ide, Graft Polymerization and Its Application, (Kobunshi Kankokai, 1977) and in Polymer Alloy (edited by the Japanese Polymer Society and published by Tokyo Kagaku Dojin, 1981). Many examples have been reported in which graft polymers having above properties were applied to reform the surface of polymers.
For example, Polymer Bulletin, Vol. 7, p. 289 (1982) states that when a graft polymer composed of a trunk (backbone polymer) of a fluoroalkyl acrylate and a branch (a grafting portion) of methyl methacrylate is formed into a film on a glass plate, the hydrophilic property and hydrophobic property of the surface of the polymer film vary greatly depending upon its environment. Thus, because of these properties, the graft polymer can impart properties not obtainable from "random copolymers", for example, wetting property, adhesion, antistatic property, and oil-repellency to the resulting hydrophilic surface, and water-repellency, reduction of friction (lubrication), and adhesion resistance to the hydrophobic surface.
Furthermore, the application of graft polymers to photography is described, for example, in U.S. Pat. No. 4,359,517, Japanese Patent Application (OPI) Nos. 75236/73 and 41490/80 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), and West German Patent Application (OLS) No. 2,311,207.
The graft polymers described in these patent documents are produced by polymerizing a dissimilar low molecular weight monomer using as an initiation point the functional groups of a linear backbone polymer. A typical example is the polymerization of acrylamide to polyvinyl alcohol catalyzed by Ce (IV), described in Takayuki Otsu and Gaetsu Kinoshita, Experimental Methods in Polymer Chemistry, (Kagaku Dojin) at page 387 (1972). Such a synthesizing method, however, generally has the disadvantage that a homopolymer of a dissimilar monomer component gets mixed and a graft polymer of high purity is difficult to obtain, and that the length and number of grafts are difficult to control. For this reason, these graft polymers have a very weak effect of exhibiting a function attributed to the multiphase structure described hereinabove, and in application to reforming the surface of polymers, they must be added in relatively large amounts. Furthermore, the inclusion of the homopolymer of a dissimilar monomer component may prevent the graft polymers from exhibiting their function. A further defect is that in a photographic system, commerical value of a graft polymer is reduced greatly owing to staining, fogging, and desensitization caused by bleeding or diffusion of the graft polymer to another layer.